Catalysts used in chemical reactions mainly have the function of increasing the reaction rate, and are industrially essential materials in the production of desired compounds. Such catalysts are selected depending on the type of each reaction in the synthesis process of chemical products, pharmaceuticals, intermediate raw materials, etc.
For example, fluoroalkanes or fluoroolefins used in heat media, refrigerants, foaming agents, etc., are known to be synthesized by vapor-phase fluorination using hydrogen fluoride, or by dehydrohalogenation. These reactions are generally performed in the presence of a catalyst (for example, see PTL 1). The catalysts used in these reactions are, for example, metal-containing fluoride, chloride, oxide, etc.; however, if such a catalyst is continuously used for a long period of time, the original performance of the catalyst is reduced due to the degradation of the catalyst itself, which may affect the reaction rate, reaction yield, etc. Therefore, regular replacement of the catalyst used in the reaction is generally performed.
As the method for recovering the catalyst used in the reaction when, for example, the reaction system contains toxic gas, such as the hydrogen fluoride mentioned above, the catalyst is removed by, for example, replacing beforehand the inside of the system with inert gas to purge the hydrogen fluoride, and then disassembling the reaction apparatus.